This invention relates to protective coatings and, more particularly, to protective coatings that include zirconium for enhanced oxidation resistance.
Components that are exposed to high temperatures, such as gas turbine engine components, typically include a protective coating system having one or more coating layers. For example, turbine blades, turbine vanes, and blade outer air seals typically include the coating system to protect from erosion, oxidation, corrosion or the like and thereby enhance durability or maintain efficient operation of the engine.
Typically, the coating system includes a metallic coating, such as a MCrAlY coating, as a “stand-alone” coating or as a bond coat for a ceramic topcoat. The metallic coating reacts with oxygen to form an adherent oxide that protects the underlying component from oxidation and corrosion. To control a rate of oxidation of the aluminum in the coating, reactive elements such as hafnium have been added to the coating composition. One drawback of using hafnium is that it may diffuse and react with elements within the component to form intermetallic phases that degrade the mechanical integrity of the components or reduce the oxidation resistance of the coating.
Accordingly, there is a need for a protective coating that is more compatible with the underlying component and a method of manufacturing the protective coating. This invention addresses those needs while avoiding the shortcomings and drawbacks of the prior art.